Bio-pharmaceutical hose

ABSTRACT

A hose for use in bio-pharmaceutical applications includes an innermost tubular layer made from a fluoropolymer material. The tubular layer has an inner, relatively smooth and pure surface that defines an opening for transfer of various media. A layer of silicone is disposed next to an outer surface of the innermost tubular layer through use of, for example, an extrusion method. The outer surface of the tubular layer may first be modified by various treatments or chemicals to facilitate the adhesion of the silicone layer thereto. The silicone material may be solid or foamed. A reinforcement layer may be disposed adjacent to an outer surface of the silicone layer. The reinforcement layer may be formed of a wire braid having gaps. An outer jacket of silicone may be attached to the reinforcement layer and to the inner silicone layer through the gaps in the reinforcement layer.

BACKGROUND OF THE INVENTION

The invention relates in general to a hose and in particular to a hosefor use in bio-pharmaceutical applications.

Pharmaceutical companies typically use hoses to transferbio-pharmaceutical materials at various locations within the process ofmanufacturing pharmaceutical products. These bio-pharmaceuticalmaterials may include laboratory and food products as well as variouschemicals. A requirement for such hoses is for the inside surface of theinnermost layer of the hose (i.e., the surface in contact with thebio-pharmaceutical materials) to be smooth throughout and of a highdegree of purity, and thus free from becoming contaminated and/orbreaking down (i.e., chemically inert) or degrading relatively quicklyover time. Typically the innermost surface of such hoses is required tobe sterilized and cleaned relatively frequently, for example, by passingpressurized superheated steam through the hose and/or by an autoclaveprocess. However, such cleaning processes tend to degrade the innermostsurface of some prior art hoses over time. Other typical requirementsfor bio-pharmaceutical hoses include, for example, resistance frompermanent kinking, a relatively high degree of flexibility, sufficienthoop strength and tensile strength, relative ease of handling andattachment to mechanical couplings, and a relatively high degree ofvacuum resistance (i.e., the resistance to being constricted whennegative pressure or suction is applied to the hose).

Prior art hoses for use in the bio-pharmaceutical industry typicallycomprise a single layer of silicone material or a multi-layered hosehaving a silicone material for the innermost tubular member. While thesilicone material tends to provide moderate levels of flexibility andkink resistance (and, thus, relative ease in handling), the innermostsurface of the silicone material nevertheless tends to becomecontaminated and/or degraded relatively quickly over time, particularlyby the repeated steam cleaning process. This results in the replacementof the silicone material hose more frequently than desired. Other priorart bio-pharmaceutical hoses have comprised a layer of a relativelyheavy or thick wall of fluoropolymer material where the layer has arelatively smooth innermost surface and a convoluted or spiral-groovedouter surface. However, oftentimes the required smooth finish of theinnermost surface of such a hose becomes undesirably compromised overtime (e.g., rippled or otherwise deformed), particularly when the hoseis flexed. Also, other smoothbore fluoropolymer hoses without aconvoluted external outer surface typically lack flexibility and arerelatively heavy and thus difficult to handle when the inner diameter ofthe hose exceeds one inch.

Still other prior art hoses achieve the required level of vacuumresistance through use of a reinforcement layer made of relatively heavyhelix wire. However, such a metallic layer tends to be relatively stiff,thereby requiring a large amount of force to flex or bend the hose.Further, when bent, the innermost surface of such a hose tends to loseits smoothness at the point of bending. In other known hoses, thesuperheated steam vapor used during the steam cleaning process permeatesor enters the matrix of the inner wall material. This tends toaccelerate the breakdown of the innermost surface of the hose.

What is needed is a bio-pharmaceutical hose having a relativelylong-lasting purity of the innermost surface through which thebio-pharmaceutical materials are transferred, while providing arelatively large amount of flexibility and resistance to kinking andsteam permeation and also providing relatively high tensile and hoopstrength and vacuum resistance, and also being easy to handle andreadily attached to mechanical couplings.

SUMMARY OF THE INVENTION

According to an aspect of the invention, a hose for use inbio-pharmaceutical applications includes an innermost tubular layer thatcomprises, for example, a fluoropolymer material. The tubular layer hasan inner, relatively smooth and pure surface that defines an opening fortransfer of various media. The innermost tubular layer may be madeelectrically-conductive by the addition of, e.g., carbon material,within the fluoropolymer material. A layer of silicone is disposed nextto an outer surface of the innermost tubular layer through use of, forexample, an extrusion method. The outer surface of the tubular layer mayfirst be modified by various treatments or chemicals to facilitate theadhesion of the silicone layer thereto. The silicone material comprisingthe layer may be solid or foamed, and its outer surface may be smooth orconvoluted or corrugated.

According to a further aspect of the invention, a reinforcement layermay be disposed adjacent to an outer surface of the silicone layer. Thereinforcement layer may comprise a yarn textile or wire braid havinggaps or interstices. Next, an outer jacket layer of silicone may beattached to the reinforcement layer, again through use of an extrusionmethod. By utilizing a liquid silicone and subsequently curing theliquid silicone to a solid state, the liquid silicone can penetrate thegaps of the reinforcement layer and, upon curing, can adhere relativelystrongly to the outer surface of the inner silicone layer.

According to yet another aspect of the invention, a plurality of hosesas described above may be arranged in a hose assembly where an outerlayer of silicone encloses the plurality of hoses.

Another aspect of the invention involves a method for making a hosewhich includes the provision of an inner tubular member made from, e.g.,a fluoropolymer material, having a smooth innermost surface. Next, asilicone layer is formed over an outer surface of the inner tubularmember preferably by a cross-head extrusion process that utilizes liquidsilicone in two separate forms, a first form of liquid siliconeincluding a liquid platinum or peroxide catalyzer; and a second form ofsilicone comprising a base silicone material having an adhesionpromoter. The two separate liquid silicone elements are extruded ontothe outer surface of the inner tubular member through pumping andmetering of the silicone elements in a certain ratio, and mixingtogether of the elements to form a liquid silicone mixture. The mixtureis extruded onto the inner tubular member through use of a cross-headdie, and then the silicone is cured thereby forming a composite tubularhose where the silicone is strongly bonded to the inner tubular member.The silicone may also be foamed or aerated to form voids in theresulting silicone layer. The silicone layer may alternatively have itsouter surface convoluted or corrugated. Optional subsequent steps mayinclude attaching a reinforcement layer comprising a wire braid to theouter surface of the inner silicone layer, where the wire braid has gapsor interstices formed therein. An outer jacket of silicone may be formedover the reinforcement layer. The outer jacket may be formed initiallyfrom liquid silicone using similar process steps to those describedabove for forming the inner silicone layer. The liquid silicone of theouter jacket penetrates the gaps in the reinforcement layer duringextrusion of the silicone onto the reinforcement layer such that theliquid silicone bonds to the outer surface of the inner silicone layer.The liquid silicone comprising the outer jacket is subsequently cured toform the multi-layered hose end product.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of preferred embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, partially broken away, of a firstembodiment of a bio-pharmaceutical hose of the present invention;

FIG. 2 is a perspective view, partially broken away, of an alternativeembodiment of the hose of FIG. 1;

FIG. 3 is a perspective view, partially broken away, of an alternativeembodiment of the hose of FIG. 1 having additional layers;

FIG. 4 is a perspective view, partially broken away, of an alternativeembodiment of a bio-pharmaceutical hose of the present invention havingoptional layers; and

FIG. 5 is an end view of a plurality of the hoses of FIGS. 1 and 3enclosed by an outer layer.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there illustrated is a preferred embodiment of ahose 10 in accordance with the present invention. The hose 10 includesan inner tubular member or liner 12 that may comprise acommercially-available fluoropolymer material such as, for example,polytetrafluoroethylene (“PTFE”), fluorinated ethylene propylene(“FEP”), perfluoroalkoxy (“PFA”), ethelyne tetrafluoroethylene (“ETFE”),polyvinylidene fluoride (“PVDF”), or polychlorotrifluoroethylene(“PCTFE”). Alternatively, the inner liner 12 may comprise a plastic suchas nylon, or another material such as a liquid crystal polymer. Theinner tubular member 12, which itself may be commercially-available, maybe formed by extrusion as a thin-walled “skin” with a preferred,exemplary thickness in the range of from 0.001 inches to 0.040 inches.The diameter of the resulting opening 14 in the member 12 (i.e., the“inner diameter”) may range, for example, from 0.125 inches to 3.0inches. As generally known to one of ordinary skill in the art, the sizeof the inner diameter of the opening 14 of the tubular member 12determines the thickness of each layer in the hose 10, including that ofthe tubular member 12.

If desired, the fluoropolymer material comprising the tubular member 12may be made electrically condudtive by the addition of carbon in theform of, for example, finely divided carbon black particles or othergraphite nanotube additives. Making the tubular member 12electrically-conductive allows the member 12 to dissipate any undesiredelectrostatic charge that may tend to build up in the hose 10,particularly in the inner tubular member 12, by the media passingthrough the opening 14 in the inner tubular member 12. For use inbio-pharmaceutical applications, the fluoropolymer materials utilizedfor the member 12 are, in general, FDA-approved materials that alsoconform to the U.S. Pharmacopia (“USP”) Class 6 purity standard. Theinner tubular member or liner 12 thus forms a relatively pure, smooth,chemical- and temperature-resistant conduit and barrier for the mediumwhich is conveyed therethrough. In particular, the fluoropolymer member12 prevents the superheated steam used in the aforementioned steamcleaning process from permeating into the material comprising the innertubular member 12 and causing degradation to such material.

An outer surface 16 of the inner tubular member 12 may be modified byexposure to various treatments and/or chemicals, including plasmadischarge, corona discharge, or laser treatment, and/or sodiumnapthalate, ammonium napthalate, or ammonia. The resulting modifiedouter surface 16 has a relatively reduced amount of surface energy,which allows for better adhesion (i.e., reduced slippage) of the outersurface 16 to an inner surface of the next layer 18 that comprises thehose 10, discussed hereinbelow.

Disposed next to the outer surface 16 of the inner tubular member 12 aspart of the hose 10 is a tubular layer 18 that comprises, in a preferredembodiment, a cross-linked silicone rubber material. To form the layer18 next to or over the inner tubular layer 12, the silicone material maybe wrapped around the outer surface 16 of the inner member 12, or may beover-molded to the outer surface 16 of the tubular member 12 byinjection molding or cross-head extrusion methods. Preferably, thesilicone material comprising the layer 18 is initially in liquid formand is cured to a solid state during the bonding process to the outersurface 16 of the tubular member 12. As a result, the silicone layer 18forms a permanent bond to the inner tubular member 12.

More specifically, in a preferred embodiment of a method aspect of theinvention using a cross-head extrusion technique, the silicone materialcomprising the layer 18 may initially include a liquid platinum orperoxide catalyzer and a separate liquid base silicone without thecatalyzer but containing an adhesion promoter to promote adhesion to theouter surface 16 of the inner tubular member 12. The base silicone maybe pigmented or clear. Both of these separate silicone elements arecommercially available from, e.g., Specialty Silicones, Inc. of BallstonSpa, N.Y. The two separate silicone elements may be extruded onto theouter surface 16 of the inner tubular member 12 using a displacementpump system that includes two separate servo-controlled gear pumps forseparately and simultaneously pumping and accurately metering the liquidsilicone elements. The speed of the gear pumps is used to achieverelatively accurate metering of the silicone elements. The gear pumpstypically pump the separate silicone elements from their containersthrough tubes or lines into a static mixing vessel or tube where thesilicone elements are mixed together repeatedly to form a resultingliquid silicone mixture. In the mixing vessel it is generally notnecessary to adjust the balance of the silicone elements. Preferably,the two separate silicone elements are mixed in a certain ratio,preferably a one-to-one ratio.

The silicone mixture then passes to a cross-head die where the mixtureis extruded at room temperature around the outer surface 16 of the innertubular member 12 in a particular profile (e.g., round or circular, asillustrated in FIG. 1). The cross-head die typically contains a negative(i.e., vacuum) pressure to remove any residual air. The inner tubularmember 12 with the silicone mixture extruded thereon may then be passedto an infrared heating system that cross-links or cures the silicone toa hardened state. The resulting composite tube 20 comprising the innertubular member 12 and the silicone layer 18 may then be quenched orcooled, thereby forming the composite tube 20 end product. During theextrusion process described above, the inner tubular member 12 may bepressurized throughout to prevent the member 12 from collapsing.

The thickness of the silicone layer 18 may be, for example, in the rangeof from 0.080 inches to 0.250 inches. However, the resulting thicknessof the layer 18 depends on the desired inner diameter of the opening 14in the tubular member 12, and, as such, the resulting layer thicknessshould be apparent to one of ordinary skill in the art in light of theteachings herein. After adhesion of the silicone layer 18 to the outersurface 16 of the tubular member 12 as described hereinabove, thecomposite tube 20 can be physically manipulated and kinked withoutcausing any lasting defect.

As illustrated in FIG. 1, the layer 18 may comprise a foamed layer wherethe silicone material comprising the layer 18 may have air or some othergas (e.g., Argon/Nitrogen) introduced into it during the cross-headextrusion technique described hereinabove (or within some othertechnique for forming the silicone layer 18) to form a closed cellfoamed or aerated construction of the layer 18, or may have a blowing ornucleating agent added to it as is known in the art to form voids in thesilicone layer 18 when viewing an outer surface 22 of the silicone layer18. Such a foamed construction gives the silicone layer 18 various knownbeneficial mechanical properties, including lighter weight and/ormaterial savings. In the alternative, the layer 18 may be of solidsilicone construction.

Advantageously, the bond between the inner tubular member 12 and thesilicone layer 18 that form the composite tube 20 is generally strongenough to provide the inner tubular member 12 with a relatively largeamount of kink resistance and flexibility, along with excellent recoveryfrom crushing and kinking without any undesired separation of the member12 and the layer 18. That is, the structural integrity of the compositetube 20 is maintained throughout typical usage of the hose 10 in variousbio-pharmaceutical applications. In addition, the bond between themember 12 and the layer 18 can withstand the typical sterilizationtemperatures utilized in repetitive steam and/or autoclave procedures.Thus, the layer 18 provides the composite tube 20 with sufficient bodyand strength to be subsequently additionally reinforced, if desired, bybraiding, as discussed hereinbelow. When flexed or bent into relativelytight bend radii, the silicone material comprising the layer 18 canstretch on the outside of the bend and compress on the inside. Thesilicone material may also provide an anchor for additional outer layersof the hose 10 to be adhered to, as discussed hereinbelow, with respectto alternative embodiments of the hose 10.

Referring to FIG. 2, an alternative embodiment of the hose 10 of FIG. 1has. the outer surface 22 of the inner silicone layer 18 of a corrugatedor convoluted structure. For example, the outer surface 22 may have asingle spiral groove formed therein, or multiple grooves formed inparallel therein. This provides the hose 10 with various beneficialfeatures, including increased flexibility and resistance to kinking, andalso relatively high tensile and hoop strength and ease of handling.

Referring to FIG. 3, an alternative embodiment of a hose 30 of thepresent invention includes the hose 10 (i.e., the composite tube 20) ofFIG. 1 having a reinforcement layer 24 attached or disposed adjacent tothe outer surface 22 of the inner silicone layer 18. The inner siliconelayer 18 is illustrated in FIG. 3 as being of solid siliconeconstruction, instead of the foamed construction of FIG. 1 or theconvoluted outer surface 22 of FIG. 2. The reinforcement layer 24 maycomprise a tubular wire braid construction and can be applied to theouter surface 22 of the silicone layer 18, for example, by knownwrapping, knitting or braiding techniques. The reinforcement layer 24may comprise a metal wire or a non-metallic (e.g., yam) textile materialsuch as cotton, polyester or aramid fiber. For example, using stainlesssteel wire with an open pitch provides relatively large gaps orinterstices between the wires, as illustrated in FIG. 1. This allows anouter jacket 26 of the hose 30, discussed hereinbelow, which mayinitially comprise uncured liquid silicone during the extrusion processdiscussed herein, to penetrate through the gaps in the wire braid andabut the outer surface 22 of the inner layer 18. When cured, thesilicone comprising the outer jacket 26 provides relatively excellentadhesion to the outer surface 22 of the inner silicone layer 18.

However, it is not required for the broadest scope of the presentinvention that the reinforcement layer 24 is provided with a wire braidwith gaps or interstices between the wires to allow the outer jacket 26to come in contact with the outer surface 22 of the inner silicone layer18. The angle of the braid (preferably, 54 degrees) and the tension atwhich the wire is applied in the reinforcement layer 24 provides thehose 30 with relatively good kink resistance when bent or flexed. Italso provides the hose 30 with excellent vacuum resistance (i.e., theresistance to collapsing of the tubular member 12 as well as the innersilicone layer 18 when negative pressure or suction is applied to thehose). Further, the tensile properties of the wire comprising thereinforcement layer 24 provides the hose 30 with the additional desiredproperties of flexural memory, suppleness and small bend radiuscapability. Also, the hoop strength and tensile strength of the hose 30are increased through use of the reinforcement layer 24, which allowsfor the relatively simple and easy attachment of the hose 30 to varioustypes of mechanical coupling devices.

As an alternative to the hose 30 comprising a separate reinforcementlayer 24, the hose 30 may omit the reinforcement layer 24. The siliconelayer 18 may instead contain relatively short fibers (e.g., aramid) toachieve the desired properties discussed above. The fibers may beintroduced into the silicone material comprising the layer 18 during theformation of the silicone layer 18, as discussed hereinabove in theparticular example of a cross-head extrusion process.

The outer jacket 26 of the hose 30 preferably comprises another layer ofsilicone that may be applied onto the reinforcement layer 24 as awrapped layer, or may be injection molded or cross-head extruded,similar to cross-head extrusion process discussed hereinabove withrespect to the formation of the inner silicone layer 18. The outerjacket 26 provides external serviceability for cleaning and protectingthe inner layers 12, 18, 24 of the hose 30 from external damage. Whenextruded onto the reinforcement layer 24, the silicone (initially inliquid form) comprising the outer jacket 26 penetrates the intersticesof the wire braid to form intimate contact with the outer surface 22 ofthe inner silicone layer 18. When cured, the liquid silicone materialprovides additional hoop strength to the composite tube 20 comprisingthe inner tubular member 12 and the inner silicone layer 18. Similar tothe inner silicone layer 18, the silicone material comprising the outerjacket 26 may be of solid construction or may be foamed by the additionof gas or a blowing agent, resulting in a closed cell structure.Further, in general when the hose 30 includes the reinforcement layer26, the outer surface of the outer jacket 26 preferably is of smoothconstruction, rather than being convoluted. In addition, a thermoplasticelastomer material may be utilized as the material of the outer jacket26 instead of silicone. The thermoplastic elastomer material may have anadhesion system formulated into it.

Referring to FIG. 4, in an alternative embodiment of the presentinvention, a hose 40 includes the inner tubular member 12 of the hoses10, 30 of FIGS. 1-3. In the hose 40, the inner layer 18 of siliconematerial is replaced by two separate layers 42, 44. A first layer 42 maycomprise a relatively thin layer of modified polypropylene. Themodifying or coupling agent may be a silane or a maleic-anhydridematerial. This material, which forms a permanent strong bond to theouter surface 16 of the inner tubular member 12, may be either injectionmolded or cross-head extruded over the outer surface 16 of the innertubular member 12, using known techniques. The second layer 44 may be athermoplastic elastomer from the olefinic family, or may be a urethane.This material can either be injection molded or cross-head extruded overan outer surface of the modified polypropylene layer 42, using knowntechniques. In general, thermoplastic elastomer materials are lessexpensive than silicone, do not need to be sterilized as often, and mayrequire less processing steps (i.e., omission of the cross-linkingstep). Next the reinforcement layer 24 and the outer jacket 26 may beformed over the layer 44, similar to their methods of formation over theinner silicone layer 18 as described hereinabove with respect to theembodiment of the hose 30 illustrated in FIG. 3.

Referring to FIG. 5, there illustrated is an assembly 50 of a pluralityhoses, specifically, hose 10 of FIG. 1 and the hose 30 of FIG. 3.However, the hose assembly 50 of FIG. 5 may comprise any combination ofthe aforementioned hoses 10, 30, 40. As illustrated in FIG. 3, the twohoses 10, 30 are disposed adjacent one another in a non-abuttingphysical relationship, and a single outer sleeve 52 is formed around thehoses 10, 30. The outer sleeve 52 may comprise a silicone rubbermaterial, similar to that of the inner layer 18 and/or the outer jacket26. The outer sleeve 52 may be formed using a similar cross-headextrusion technique described hereinabove with respect to the formationof the inner silicone layer 18, or by some other methods known to one orordinary skill in the art.

With respect to the overall thickness of the hose 10, 30, 40 of theembodiments disclosed and illustrated herein, for an inner diameter of1.0 inches, the resulting exemplary thickness of the entirety of thehose 10, 30, 40 is approximately 0.250 inches. However, it should beapparent to one of ordinary skill in the art that the thickness of thehose 10, 30, 40 can vary depending not only on the desired innerdiameter of the opening 14 but on the number and thickness of thevarious layers utilized in the construction of the hose 10, 30, 40.

The hose 10, 30, 40 of the present invention has been described for usein bio-pharmaceutical applications. However, the hose is not limited assuch. Instead, the hose 10, 30, 40 of the present invention may find usein various non-bio-pharmaceutical applications where is may be desiredto utilize a hose having the physical characteristics and resultingbenefits of that described herein.

Although the present invention has been illustrated and described withrespect to several preferred embodiments thereof, various changes,omissions and additions to the form and detail thereof, may be madetherein, without departing from the spirit and scope of the invention.

1-20. (canceled)
 21. A hose comprising: an innermost tubular member thatdefines an opening therein and having an inner surface and an outersurface, where the inner surface is smooth throughout, and where theinnermost tubular member comprises a fluoropolymer material; an innerlayer of silicone adjacent to and bonded to the outer surface of theinnermost tubular member, the inner layer of silicone having an outersurface; a wire braided reinforcement layer adjacent to the outersurface of the inner silicone layer, wherein gaps between wires of thereinforcement layer are larger than a diameter of said wires; an outersilicone jacket adjacent to the reinforcement layer, wherein the outersilicone jacket penetrates through said gaps between said wires of thereinforcement layer onto the outer surface of the inner silicone layer,wherein the outer silicone jacket is bonded to the outer surface of theinner silicone layer.
 22. The hose of claim 21 wherein the outersilicone jacket is foamed using gas to form voids in the outer siliconejacket.
 23. The hose of claim 21 wherein the innermost tubular member isa thin walled tubular member having a thickness between 0.001 inches and0.040 inches.
 24. The hose of claim 23 wherein the innermost tubularmember is pressurized while the inner layer of silicone is formed on theouter surface of the thin walled tubular member.
 25. The hose of claim21 wherein the outer silicone jacket is applied by extrusion.
 26. A hosecomprising: an innermost tubular member that defines an opening thereinand having an inner surface and an outer surface, wherein the innermosttubular member comprises a fluoropolymer material; forming an innerlayer of silicone adjacent to and bonded to the outer surface of theinnermost tubular member, the inner layer having an outer surface; awire braid layer adjacent to an outer surface of the inner siliconelayer, wherein an area of one of said interstices is greater than across-sectional area of one of said wires; an outer silicone jacketadjacent to the reinforcement layer, wherein the outer silicone jacketpenetrates through said interstices of the wire braid onto the outersurface of the inner silicone layer to bond the outer silicone jacket tothe outer surface of the inner silicone layer.
 27. The hose of claim 26wherein the outer silicone jacket is foamed using gas to form voids inthe outer silicone jacket.
 28. The hose of claim 26 wherein theinnermost tubular member is a thin walled tubular member having athickness between 0.001 inches and 0.040 inches.
 29. The hose of claim28 wherein the innermost tubular member is pressurized while the innerlayer of silicone is formed on the outer surface of the thin walledtubular member.
 30. The hose of claim 26 wherein the outer siliconejacket is applied by extrusion.